This invention relates to an crankcase and journal arrangement for an internal combustion engine and more particularly to an improved compact and high strength arrangement for journaling a crankshaft for an engine.
It is well known that internal combustion engines, particularly those which are employed as power units in motor vehicles, should be very compact in nature. This is particularly true when the engine is positioned transversely in the engine compartment, as is the current practice in many types of front wheel drive vehicles or rear engine, rear wheel drive vehicles. In order to provide such a compact assembly, it has been proposed to employ an engine arrangement wherein the crankshaft of the engine does not directly output the drive for the vehicle. Rather, an output shaft is journaled for rotation about an axis parallel to the crankshaft and is driven from the crankshaft and supplies the motive power for the vehicle. Such arrangements provide certain advantages in compact assembly.
In conjunction with such arrangements, the output shaft need not have the same length as the engine crankshaft. In fact, it is desirable to provide an output shaft that is shorter in length than the engine crankshaft so as to reduce the overall size of the engine. However, it is also advantageous to rotatably journal the output shaft within the same crankcase chamber as the crankshaft. If this is done with conventional arrangements, the total crankcase size becomes quite large and, furthermore, the advantages of a compact engine construction can be lost.
It is, therefore, a principal object of this invention to provide an improved crankshaft and output shaft arrangement and associated crankcase for an internal combustion engine that provides a compact assembly.
It is a further object of this invention to provide an improved and compact arrangement for journaling a crankshaft and an output shaft for driving a vehicle within the crankcase of an internal combustion engine.
It is yet another object of this invention to provide an improved, compact output shaft drive system for an engine wherein the output shaft is contained within the crankcase of the engine and yet provide a compact engine construction.
In connection with the journaling arrangement for a engine crankshaft, it is a conventional practice to provide a journal arrangement for the crankshaft which includes bearing portions that are formed by the cylinder block and which cooperate with bearing cap affixed to the cylinder block for journaling the crankshaft. The use of separate bearing caps and individual ones for each crankshaft bearing can reduce the rigidity of the engine. It has been proposed, however, to use a construction wherein a plurality of the bearing caps are formed by a common member that is fixed to the cylinder block. However, when this has been done, this member is contained within a separate crankcase pa that is fixed to the cylinder block. Thus the overall construction becomes quite complicated. Furthermore, the use of such double members does not increase the rigidity of the engine as much as might be hoped.
It is, therefore, a still further object of this invention to provide an improved arrangement for journaling a crankshaft within a engine wherein all of the bearing caps are formed from a common member and yet a separate..closure for the crankcase is not necessary.
It is a further object of this invention to provide an improved combined crankcase closure and bearing cap arrangement for an internal combustion engine.
It has been previously noted that certain advantages can be enjoyed in compaction of the engine package if a separate output shaft is driven from the crankshaft and supplies the output power from the engine. Where this is done, it is desirable to drive this output shaft from a point between the ends of the crankshaft so as to provide a more compact construction. One way this can be done is by providing a gear drive for the output shaft with the gear drive being formed by an integral gear formed on the crankshaft at one of the throws. However, when this is done, the balancing arrangement for the crankshaft can be upset.
It is, therefore, a further object of this invention to provide an improved crankshaft for an internal combustion engine that has a drive for driving an output shaft from a point at one of the journals of the engine and wherein the balancing of the crankshaft is facilitated.